PHP has removed all mysql_ functions and replaced with mysqli. And I don't think there's easy way to create all mysql functions or replace the old functions with mysqli functions. Is there any particular reason why you would need PHP v7?

I just noticed that in the newest version of cmsb under General Settings > Advanced Settings, there is a checkbox "Legacy MySQL Support" that adds the support to old mysql functions even if they are deprecated and removed.

In that case, I think you can also try backup the current cmsb and create a separate latest version of cmsb with all add-ons and legacy mysql support. Then test to see if the newest version works fine for you.

About the forum notifications, I'm very sure that I didn't getting any email from the forum at all. I have control on my spam folder.There is something on your side. Can you check for the email with ht1080z name in it please?